The present invention relates to silicone release coating compositions having superior release properties when cured by the application of heat. More specifically this invention relates to silicone release coating compositions having superior curability and storage stability at room temperature and which produce uniform coatings when used in thin film form on an applicator roll.
Various heat curable organopolysiloxane compositions obtained by using an alkenyl-containing diorganopolysiloxane, an organohydrogenpolysiloxane, and a platinum group metal catalyst as their main components and admixing a reaction retardant thereto have been disclosed. These compositions, with all the components mixed in advance, could be stored for an extended period of time, however, because of this, storage stabilizers, in other words, reaction retardants, played an important role. Compounds having double carbon-carbon bonds or triple carbon-carbon bonds are known as commonly used reaction retardants, for example, ethylene tetrachloride as a reaction retardant was disclosed in U.S. Pat. No. 3,383,356, 3-methyl-1-butyne-3-ol was disclosed in U.S. Pat. No. 3,445,420, organosilicon compounds having the formula ##STR1## were disclosed in Japanese Patent Publication No. 64-2627 (2627/1989), organosilicon compounds having the formula: ##STR2## were disclosed in Japanese Patent Publication No. 01-12786 (12786/1989), and organosiloxanes containing acetylenically unsaturated groups were disclosed in Japanese Patent Publication No. 64-51466 (51466/1989) having the formula: ##STR3## However, the respective action of these compounds was insufficient, and, as a result, heat curable organopolysiloxane compositions obtained by admixing them as storage stabilizers had various defects, such as an increase in viscosity caused by low stability at room temperature, gelling when used in thin film form on an applicator roll, which rendered uniform coating impossible, and low peeling stability when cured under low-temperature conditions.